III–V nanowires (NWs) possess great potential for use in future semiconductor technology. Alloying with dilute amounts of nitrogen provides further flexibility in tuning their material properties. In this study, we report on successful in situ nitrogen incorporation into GaP(N) NWs during growth via the Au-catalyzed vapor-liquid-solid (VLS) mechanism. The impact of the nitrogen precursur unsymmetrical dimethyl hydrazine (UDMH) on morphology was found to be overall beneficial as it strongly reduces tapering. Analysis of the crystal structure of NWs with and without N reveals zinc blende structure with an intermediate amount of stacking faults (SF). Interestingly, N incorporation leads to segments completely free of SFs, which are related to dislocations transverse to the growth direction.

Pseudomorphic planar III-V transition layers greatly facilitate the epitaxial integration of vapor-liquid-solid grown III-V nanowires (NW) on Si(111) substrates. Heteroepitaxial (111) layer growth, however, is commonly accompanied by the formation of rotational twins. We find that rotational twin boundaries (RTBs), which intersect the surface of GaP/Si(111) heterosubstrates, generally cause horizontal NW growth and may even suppress NW growth entirely. Away from RTBs, the NW growth direction switches from horizontal to vertical in the case of homoepitaxial GaP NWs, whereas heteroepitaxial GaAs NWs continue growing horizontally. To understand this rich phenomenology, we develop a model based on classical nucleation theory. Independent of the occurrence of RTBs and specific transition layers, our model can generally explain the prevalent observation of horizontal III-V NW growth in lattice mismatched systems and the high crystal quality of horizontal nanowires.

Light‐induced degradation (LID) in boron‐doped Czochralski grown (CZ) silicon is a severe problem for silicon devices such as solar cells or radiation detectors. Herein, boron‐doped CZ silicon is investigated by low‐temperature photoluminescence (LTPL) spectroscopy. An LID‐related photoluminescence peak is already found while analyzing indium‐doped p‐type silicon samples and is associated with the ASi–Sii defect model. Herein, it is investigated whether a similar peak is present in the spectra of boron‐doped p‐type CZ silicon samples. The presence of change in the photoluminescence signal intensity due to activation of the boron defect is investigated as well. Numerous measurements on boron‐doped samples are made. For this purpose, samples with four different boron doping concentrations are analyzed. The treatments for activation of the boron defect are based on the LID cycle. During an LID cycle, an additional peak or shoulder neither in the areas of the boron‐bound exciton transverse acoustic and nonphonon‐assisted peaks (BTA, BNP) nor in the area of the boron‐bound exciton transverse optical phonon‐assisted peak (BTO) is found. The defect formation also does not lead to a lower photoluminescence (PL) intensity ratio BTO(BE)/ITO(FE).

The ASi–Sii defect model as one possible explanation for light‐induced degradation (LID) in typically boron‐doped silicon solar cells, detectors, and related systems is discussed and reviewed. Starting from the basic experiments which led to the ASi–Sii defect model, the ASi–Sii defect model (A: boron, or indium) is explained and contrasted to the assumption of a fast‐diffusing so‐called “boron interstitial.” An LID cycle of illumination and annealing is discussed within the conceptual frame of the ASi–Sii defect model. The dependence of the LID defect density on the interstitial oxygen concentration is explained within the ASi–Sii defect picture. By comparison of electron paramagnetic resonance data and minority carrier lifetime data related to the assumed fast diffusion of the “boron interstitial” and the annihilation of the fast LID component, respectively, the characteristic EPR signal Si‐G28 in boron‐doped silicon is related to a specific ASi–Sii defect state. Several other LID‐related experiments are found to be consistent with an interpretation by an ASi–Sii defect.

Fast silicon detectors are crucial for a lot of applications, [1] e.g., the experiments at large hadron collider (LHC) at CERN to obtain timeresolved trajectories of particles. A concept to realize such fast silicon detectors are the low-gain avalanche detectors (LGAD). They combine the advantages of normal n-i-p-diodes such as a low noise with a large signal of avalanche multiplication diodes. [2] LGADs operate with a gain of about 10. The avalanche multiplication region is usually obtained by deep boron doped layers. [3] Nevertheless, these LGADs have a drawback if they are irradiated. The gain layer "disappears" after irradiation as a consequence of a deactivation of the gain layer doping species, which is usually boron. [4,5] This means that, e.g., boron, loses after irradiation its properties as an acceptor to provide a negative space charge.In this contribution, the focus is first on LGAD device manufacturing at CiS. Afterward, an experiment is described and discussed, which investigates the acceptor removal phenomenon for the three acceptors boron, gallium, and indium in silicon. Therefore, boron, gallium, and indium were implanted into silicon. Additionally, coimplantation of carbon, oxygen, nitrogen, and fluorine was made. It was found in the literature that for carbon co-implantation the acceptor removal effect can be reduced. [6] Therefore, this study investigates different co-implantation species if they have an impact on the acceptor removal phenomenon. The samples underwent an activation anneal and were then investigated by 4-point-probe (4pp), low temperature photoluminescence spectroscopy (LTPL) and secondary ion mass spectrometry (SIMS) before and after irradiation with electrons and protons.